A tenth of the panes, a fifth of the time
The defaults describe an ordinary commercial stop: 60 panes you can reach standing up, 30 that need a pole or a step ladder, and 8 over a stairwell and an entrance canopy that need a ladder set and moved. Ninety-eight panes, inside and out.
At 0.9, 1.8 and 3.5 minutes a pane the outside pass is 136 minutes and the inside pass, 25 percent slower, is 170. The eight ladder panes are 8.2 percent of the count and 63 of those 306 pane-minutes — 20.6 percent of the glass time. They cost two and a half times their share, and if every one of them could be reached from the floor the day would shorten by fifty minutes.
That ratio is the reason a survey sheet that only records a pane count produces quotes that are wrong in both directions. A building with all its glass at ground level and a building with the same count spread over a stairwell are not the same job and are not close.
The parts that are not glass
Frames, sills and tracks at 0.4 minutes a pane add 39 minutes, and they are charged once per pane no matter how many faces get cleaned. Twenty screens at a minute and a half add another 30. Three separate elevations at six minutes each to set up and break down add 18. That is 87 minutes — an hour and a half of a job that has nothing to do with cleaning glass, and the part most commonly left off a quote entirely.
The whole stop comes to 6h 33m on site. Add twenty minutes to get to the next one and it is 6h 53m door to door, against a seven hour productive day. This job is the day. There is no second stop, which is worth knowing before three of them are booked for a Tuesday.
Panes per hour is an output, not an input
The blended figure here works out at just under 15 panes an hour on site, or 4.01 minutes a pane. Neither number was entered anywhere. They fall out of the tier split, the second pass, the frames, the screens and the setups, and they would come out completely differently on a building with the same pane count and a different access mix.
This is why a panes-per-hour figure borrowed from anyone else is close to useless. It is a summary of somebody else's building. The inputs worth borrowing are the three per-tier minutes, and even those only after you have timed twenty panes yourself and found out how far off the borrowed ones were.
Where it is wrong
It treats every pane in a tier as the same. A shopfront light and a stairwell casement are both one pane here, and if a building mixes them badly the average minute figure describes neither. Split the survey into two runs of the page rather than averaging.
It also has no weather in it, no first-clean penalty for glass that has not been touched in three years, and no allowance for the twenty minutes lost to a facilities manager who wants a chat. Those are real and they are not modelled. The honest use of the output is as the floor of the estimate, with the ladder line read carefully, because that is where the surprises live.
Questions people ask
How long does it take to clean 98 panes?
On the figures in the form, 6h 33m on site and 6h 53m door to door — but only because 8 of those panes need a ladder set and moved. Move those eight to floor level and the same count comes in fifty minutes quicker. The pane count alone does not predict the time, which is why the form splits it by access before it does anything else.
How many minutes per pane should I use?
Whatever your own stopwatch says, on your own kit, over at least twenty panes. The form ships with 0.9, 1.8 and 3.5 minutes for the three access tiers as placeholders to overwrite, and publishes no figure of its own. A borrowed number describes somebody else's building, somebody else's squeegee and somebody else's glass.
Why does the inside pass take longer than the outside?
Furniture to shift, a drop cloth to lay, blinds to lift, and people at desks to work around — none of which exists on the outside face. The form applies a 25 percent uplift as a placeholder. Time an inside pass and an outside pass on the same elevation once and you will have your own figure, and it is frequently higher than 25 percent in an occupied office.
How many window cleaning jobs fit in a day?
Divide the productive day by the door-to-door time for one stop. At the defaults, one stop is 6h 53m and the day is seven hours, so the answer is one. Smaller stops multiply, but the travel between them is counted per stop, which is why four small jobs across a town rarely add up to the same billable hours as one large one.
Does the calculator account for working at height?
Only in minutes, and only the minutes you enter. It has no view on what access is safe or permitted on any building — that is decided by whoever controls the site and by the rules that apply where you work. Ladders, poles near overhead lines, wet ground and roof edges are real hazards, named here and given no procedure.